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Comment by Dr. Krishna Kumari Challa on August 23, 2022 at 8:23am

Researchers discover a material that can learn like the brain

Researchers have discovered that Vanadium Dioxide (VO₂), a compound used in electronics, is capable of "remembering" the entire history of previous external stimuli. This is the first material to be identified as possessing this property, although there could be others.

A PhD student made a chance discovery during his research on phase transitions in Vanadium Dioxide (VO₂). VO₂ has an insulating phase when relaxed at room temperature, and undergoes a steep insulator-to-metal transition at 68 °C, where its lattice structure changes. Classically, VO₂ exhibits a volatile memory: "the material reverts back to the insulating state right after removing the excitation" . For his thesis, he set out to discover how long it takes for VO₂ to transition from one state to another. But his research led him down a different path: after taking hundreds of measurements, he observed a memory effect in the material's structure.

In his experiments, the student applied an electric current  to a sample of VO₂. The current moved across the material, following a path until it exited on the other side. As the current heated up the sample, it caused the VO₂ to change state. And once the current had passed, the material returned to its initial state.

He then applied a second current pulse to the material, and saw that the time it took to change state was directly linked to the history of the material. The VO₂ seemed to 'remember' the first phase transition and anticipate the next. The researchers didn't expect to see this kind of memory effect, and it has nothing to do with electronic states but rather with the physical structure of the material. It's a novel discovery: no other material behaves in this way.

The researchers went on to find that VO₂ is capable of remembering its most recent external stimulus for up to three hours. The memory effect could in fact persist for several days, but we don't currently have the instruments needed to measure that.

The research team's discovery is important because the memory effect they observed is an innate property of the material itself. Engineers rely on memory to perform calculations of all kinds, and materials that could enhance the calculation process by offering greater capacity, speed and miniaturization are in high demand. VO₂ ticks all three of these boxes. What's more, its continuous, structural memory sets it apart from conventional materials that store data as binary information dependent on the manipulation of electronic states.

The researchers performed a host of measurements to arrive at their findings. They also corroborated their results by applying the new method to different materials at other laboratories around the world. This discovery replicates well what happens in the brain, as VO₂ switches act just like neurons.

Mohammad Samizadeh Nikoo, Electrical control of glass-like dynamics in vanadium dioxide for data storage and processing, Nature Electronics (2022). DOI: 10.1038/s41928-022-00812-z. www.nature.com/articles/s41928-022-00812-z

Comment by Dr. Krishna Kumari Challa on August 22, 2022 at 10:13am

How Quinine Fights Malaria

Comment by Dr. Krishna Kumari Challa on August 20, 2022 at 10:14am

Non-nutritive sweeteners affect human microbiomes and can alter glycemic responses

Since the late 1800s non-nutritive sweeteners have promised to deliver all the sweetness of sugar with none of the calories. They have long been believed to have no effect on the human body, but researchers publishing in the journal Cell on August 19 challenge this notion by finding that these sugar substitutes are not inert, and, in fact, some can alter human consumers' microbiomes in a way that can change their blood sugar levels.

In 2014 researchers found that non-nutritive sweeteners affected the microbiomes of mice in ways that could impact their glycemic responses. They were interested in whether these results would also be found in humans.

To address this important question, the researchers  carefully screened over 1,300 individuals for those who strictly avoid non-nutritive sweeteners in their day-to-day lives, and identified a cohort of 120 individuals. These participants were broken into six groups: two controls and four who ingested well below the FDA daily allowances of either aspartame, saccharin, stevia, or sucralose.

In subjects consuming the non-nutritive sweeteners, scientists could identify very distinct changes in the composition and function of gut microbes, and the molecules they secret into peripheral blood. This seemed to suggest that gut microbes in the human body are rather responsive to each of these sweeteners.

When they looked at consumers of non-nutritive sweeteners as groups, they found that two of the non-nutritive sweeteners, saccharin and sucralose, significantly impacted glucose tolerance in healthy adults. Interestingly, changes in the microbes were highly correlated with the alterations noted in people's glycemic responses.

To establish causation, the researchers transferred microbial samples from the study subjects to germ-free mice—mice that have been raised in completely sterile conditions and have no microbiome of their own.

The results were quite striking. In all of the non-nutritive sweetener groups, but in none of the controls, when the researchers transferred into these sterile mice the microbiome of the top responder individuals collected at a time point in which they were consuming the respective non-nutritive sweeteners, the recipient mice developed glycemic alterations that very significantly mirrored those of the donor individuals. In contrast, the bottom responders' microbiomes were mostly unable to elicit such glycemic responses. These results suggest that the microbiome changes in response to human consumption of non-nutritive sweetener may, at times, induce glycemic changes in consumers in a highly personalized manner.

The effects of the sweeteners will vary person to person because of the incredibly unique composition of our microbiome.

 Eran Elinav, Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance, Cell (2022). DOI: 10.1016/j.cell.2022.07.016. www.cell.com/cell/fulltext/S0092-8674(22)00919-9

Comment by Dr. Krishna Kumari Challa on August 20, 2022 at 8:19am

How the brain gathers threat cues and turns them into fear

Scientists have uncovered a molecular pathway that distills threatening sights, sounds and smells into a single message: Be afraid. A molecule called CGRP enables neurons in two separate areas of the brain to bundle threatening sensory cues into a unified signal, tag it as negative and convey it to the amygdala, which translates the signal into fear.

The research, published in Cell Reports on August 16, 2022, may lead to new therapies for fear-related disorders such as post-traumatic stress disorder (PTSD) or hypersensitivity disorders such as autism, migraines and fibromyalgia.

The brain pathway researchers now discovered works like a central alarm system. The CGRP neurons are activated by negative sensory cues from all five senses—sight, sound, taste, smell and touch. Identifying new threat pathways provides insights into treating fear-related disorders.

Most external threats involve multisensory cues, such as the heat, smoke and smell of a wildfire. Previous research showed that different pathways independently relay sound, sight, and touch threat cues to multiple brain areas. A single pathway that integrates all these cues would be beneficial to survival, but no one had ever found such a pathway.

Previous research also showed that the amygdala, which initiates behavioral responses and forms fear memories to environmental and emotional stimuli, receives heavy input from brain regions that are laden with a chemical associated with aversion, the neuropeptide CGRP (calcitonin gene-related peptide).

Based on these two pools of research,  researchers now proposed that CGRP neurons, found especially in subregions of the thalamus and the brainstem, relay multisensory threat information to the amygdala. These circuits may both generate appropriate behavioral responses and help form aversive memories of threat cues.

The researchers conducted several experiments to test their hypotheses. They recorded CGRP neuron activity using single-cell calcium imaging while presenting mice with multisensory threat cues, enabling the researchers to pinpoint which sensory modality involved which sets of neurons. They determined the path the signals took after leaving the thalamus and brainstem using different colored fluorescent proteins. And they conducted behavioral tests to gauge memory and fear.

Taken together, their findings show that two distinct populations of CGRP neurons—one in the thalamus, one in the brainstem—project to nonoverlapping areas of the amygdala, forming two distinct circuits. Both populations encode threatening sights, sounds, smells, tastes and touches by communicating with local brain networks. Finally, they discovered that both circuits are necessary for forming aversive memories—the kind that tell you, "Stay away."

While mice were used in this study, the same brain regions also abundantly express CGRP in humans. This suggests that the circuits reported here may also be involved in threat perception-related psychiatric disorders.

https://www.cell.com/cell-reports/fulltext/S2211-1247(22)01039-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2211124722010397%3Fshowall%3Dtrue

Comment by Dr. Krishna Kumari Challa on August 20, 2022 at 7:45am

Can a human with a spinal cord injury walk and run? Discovering clues with neuromorphic technology

 An international research team  has succeeded in recovering muscle movements in a model of paralyzed mice through organic artificial nerves. The result was published in Nature Biomedical Engineering.

The nerves, which are essential for life activities as well as having a significant impact on quality of life, are easily damaged by various causes such as physical injury, genetic causes, secondary complications, and aging. In addition, once nerves are damaged they are difficult to reconstruct, and some or all their bodily functions are permanently lost due to poor bio-signaling.

Among the various methods for rehabilitation in patients with neurological damage, Functional Electrical Stimulation (FES), which is currently actively used in clinical practice, uses computer-controlled signals. Through this setup, electrical stimulation is applied to muscles that are no longer arbitrarily controllable in patients with neuropathy to induce muscle contraction, resulting in functionally useful movements in the biological body even though they are confined in a specific space. However, this conventional approach has limitations that are not suitable for long-term use in patients' daily lives because they involve complex digital circuits and computers for signal processing to stimulate muscles, consuming a lot of energy and poor biocompatibility in the process.

To solve the problem, the research team succeeded in controlling the leg movement of mice only with artificial nerves without a complex and bulky external computer using stretchable, low-power organic nanowire neurormorphic devices that emulate the structure and function of bio nerve fibers. The stretchable artificial nerve consists of a strain sensor that simulates a proprioceptor which detects muscle movements, an organic artificial synapse that simulates a biological synapse, and a hydrogel electrode for transmitting signals to the leg muscles.

The researchers adjusted the movement of the mouse legs and the contraction force of the muscles according to the firing frequency of the action potential transmitted to the artificial synapse with a principle similar to that of the biological nerve, and the artificial synapse implements smoother and more natural leg movements than the usual FES.

In addition, the artificial proprioceptor detects the leg movement of the mouse and gives real-time feedback to the artificial synapse to prevent muscle damage due to excessive leg movement.

The researchers succeeded in allowing a paralyzed mouse to kick the ball or walk and run on the treadmill. Furthermore, the research team showed the applicability of artificial nerves in the future for voluntary movement by sampling pre-recorded signals from the motor cortexes of moving animals and moved the legs of mice through artificial synapses.

The researchers discovered a new application feasibility in the field of neuromorphic technology, which is attracting attention as a next-generation computing device by emulating the behavior of a biological neural network.

https://www.nature.com/articles/s41551-022-00918-x

https://www.eurekalert.org/news-releases/961673

Comment by Dr. Krishna Kumari Challa on August 19, 2022 at 9:06am

Turning to the laws of physics to study how cells move

Scientists have long been concerned with trying to understand how cells move, for example in pursuit of new ways to control the spread of cancer. The field of biology continues to illuminate the infinitely complex processes by which collections of cells communicate, adapt, and organize along biochemical pathways.

Turning to the laws of physics, researchers have taken a fresh look at how cells move, revealing similarities between the behaviour of cell tissue and the simplest water droplets. They have taken a different perspective on how cell motion is determined by the properties of the tissues they're in rather than how they act individually.

Published in Physical Review Letters, the researchers’ initial experiments used mechanical techniques to measure the surface tension of a simple "ball" of cell tissue to reveal similarities with the thermo-dynamic properties of water droplets, but with noticeable differences.

With a water droplet the surface tension is constant and doesn't change with droplet size.

However, the scientists found that in the case of a "droplet" of cancer cells surface tension was size dependent—the smaller the tissue the higher the surface tension, and the higher the pressure within the tissue.

Next, they applied a surface tension gradient to show that cells within the tissue moved rapidly and collectively, much like the way the surface of water moves when detergent is added. Their findings were published in Physical Review Fluids.

This so called "Marangoni" effect occurs when the forces at the surface of a tissue drive the motion of cells inside.

To complete the puzzle, the scientists allowed the tissue to adhere to a surface, mimicking the way a tumor grows and spreads. Cells emerged from the ball of tissue like water droplets "wetting" a receptive—or hydrophilic—surface. In some conditions, the wetting increased the internal pressure of the tissue, helping to push cells out.

Published today in Physical Review X, these findings cast new light on the degree to which cells "migrate" or whether pressure from surface tension promotes cell movement.

This new work shows that the bulk properties of tissue, including the surface tension and pressure, matter when it comes to the ability of cells to migrate out of a model tumor.

M. S. Yousafzai et al, Active Regulation of Pressure and Volume Defines an Energetic Constraint on the Size of Cell Aggregates, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.048103

Vikrant Yadav et al, Gradients in solid surface tension drive Marangoni-like motions in cell aggregates, Physical Review Fluids (2022). DOI: 10.1103/PhysRevFluids.7.L031101

Muhammad Sulaiman Yousafzai et al, Cell-Matrix Elastocapillary Interactions Drive Pressure-Based Wetting of Cell Aggregates, Physical Review X (2022). DOI: 10.1103/PhysRevX.12.031027

Comment by Dr. Krishna Kumari Challa on August 19, 2022 at 8:57am

Swarms of microrobots could be solution to unblocking medical devices in body

Swarms of microrobots injected into the human body could unblock internal medical devices and avoid the need for further surgery, according to new research .

The study is the first-time scientists have developed magnetic microrobotics to remove deposits in shunts—common internal medical devices used to treat a variety of conditions by draining excess fluid from organs.

Shunts are prone to malfunctioning, often caused by blockages due to a build-up of sediment. The sediment not only narrows and obstructs liquid passing through the shunt, but it also affects the shunt's flexibility. This leads to patients needing repeated, invasive surgeries throughout their lives either to replace the shunt or use a catheter to remove the blockage.

However, this new research  has shown there could be a wireless, non-invasive alternative to clearing the blockage in a shunt. It has shown that a swarm of hundreds of microrobots—made of nano size magnetic nanoparticles—injected into the shunt could remove the sediment instead.

Once the magnetic microrobots are injected into the shunt they can be moved along the tube to the affected area using a magnetic field, generated by a powerful magnet on the body's surface. The swarm of microrobots can then be moved so they scrape away the sediment, clearing the tube.

"The non-invasive nature of this method is a considerable advantage to existing methods as it will potentially eliminate the risk of surgery and a surgery-related infection, thereby decreasing recovery time.

With each microrobot smaller than the width of a human hair, once the swarm has done its job, it can either be guided to the stomach via a magnetic field or bodily fluid, so they leave the body naturally. Because the microrobots have very high biocompatibility they will not cause toxicity.

The research also found a direct relation between the strength of the magnetic field and the success of scraping away the sediment in the shunt.

This is the first proof-of-concept experiment using microswarms for opening a blockage in a shunt.

A. Moghanizadeh et al, A novel non-invasive intervention for removing occlusions from shunts using an abrading magnetic microswarm, IEEE Transactions on Biomedical Engineering (2022). DOI: 10.1109/TBME.2022.3192807

Comment by Dr. Krishna Kumari Challa on August 19, 2022 at 8:14am

'Forever chemicals' destroyed by simple new method

PFAS, a group of manufactured chemicals commonly used since the 1940s, are called "forever chemicals" for a reason. Bacteria can't eat them; fire can't incinerate them; and water can't dilute them. And, if these toxic chemicals are buried, they leach into surrounding soil, becoming a persistent problem for generations to come.

Now chemists have done the seemingly impossible. Using low temperatures and inexpensive, common reagents, the research team developed a process that causes two major classes of PFAS compounds to fall apart, leaving behind only benign end products. The simple technique potentially could be a powerful solution for finally disposing of these harmful chemicals, which are linked to many dangerous health effects in humans, livestock and the environment.

Even just a tiny, tiny amount of PFAS causes negative health effects, and it does not break down. We can't just wait out this problem.

The secret to PFAS's indestructibility lies in its chemical bonds. PFAS contains many carbon-fluorine bonds, which are the strongest bonds in organic chemistry. As the most electronegative element in the periodic table, fluorine wants electrons, and badly. Carbon, on the other hand, is more willing to give up its electrons.

"When you have that kind of difference between two atoms—and they are roughly the same size, which carbon and fluorine are—that's the recipe for a really strong bond.

Scientists now  found a weakness. PFAS contains a long tail of unyielding carbon-fluorine bonds. But at one end of the molecule, there is a charged group that often contains charged oxygen atoms. Researchers targeted this head group by heating the PFAS in dimethyl sulfoxide—an unusual solvent for PFAS destruction—with sodium hydroxide, a common reagent. The process decapitated the head group, leaving behind a reactive tail.

That triggered all these reactions, and it started spitting out fluorine atoms from these compounds to form fluoride, which is the safest form of fluorine.

After discovering the PFAS degradation conditions, researchers also discovered that the fluorinated pollutants fall apart by different processes than generally assumed. A simulation showed that PFAS actually falls apart two or three carbons at a time—a discovery that matched the researchers' experiments. By understanding these pathways, researchers can confirm that only benign products remain. This new knowledge also could help guide further improvements to the method.

Brittany Trang et al, Low-temperature mineralization of perfluorocarboxylic acids, Science (2022). DOI: 10.1126/science.abm8868. www.science.org/doi/10.1126/science.abm8868

Comment by Dr. Krishna Kumari Challa on August 18, 2022 at 10:38am

Modern pesticides damage the brain of bees so they can't move in a straight line

The challenge to let people walk back and forth in a straight line isn't just used by police to test if drivers are intoxicated: it's also used by neurologists to diagnose neurological disorders like ataxia, where parts of the brain that coordinate movement are impaired. Now, researchers use an insect version of this challenge to show for the first time that modern pesticides damage the nervous system of honeybees so that it becomes hard for them to walk in a straight line. The results are published in Frontiers in Insect Science.

The commonly used insecticides like sulfoxaflor and the neonicotinoid imidacloprid can profoundly impair the visually guided behavior of honeybees. New research results are reason for concern because the ability of bees to respond appropriately to visual information is crucial for their flight and navigation, and thus their survival.

The results add to what the Food and Agriculture Organization of the United Nations and the World Health Organization have called the "rapidly growing body of evidence [which] strongly suggests that the existing levels of environmental contamination [from neonicotinoid pesticides] are causing large-scale adverse effects on bees and other beneficial insects."

The researchers also show with molecular techniques that pesticide-exposed bees tended to have elevated proportion of dead cells in parts of the brain's optic lobes, important for processing visual input. Likewise, key genes for detoxification were dysregulated after exposure.

Rachel H. Parkinson et al, Honeybee optomotor behaviour is impaired by chronic exposure to insecticides, Frontiers in Insect Science (2022). DOI: 10.3389/finsc.2022.936826

Comment by Dr. Krishna Kumari Challa on August 18, 2022 at 10:32am

Adults who, as children, had half their brain removed still able to score well with face and word recognition

A team of researchers at Carnegie Mellon University's Department of Psychology and Neuroscience Institute has found that adults who had a hemispherectomy as a child scored surprisingly well on face and word recognition tests. Their paper is posted on the bioRxiv preprint server. In epilepsy, abnormal brain activity results in chronic seizures. Some people respond well to medication and others due not; for example, some people experience seizures so often that they become incapacitating. Some young patients in these circumstances are given the option of undergoing a hemispherectomy, the complete removal of the left or right hemisphere of the brain. Prior research has shown that these procedures, when done at a very young age, allow most patients to retain their IQ and their ability to communicate and live relatively normal lives. In sharp contrast, damage to either hemisphere, much less removal of one or the other in adults, leads to severe symptoms or death. In this new effort, the researchers sought to learn more about the cognitive abilities of adults who had undergone a hemispherectomy. Forty subjects were shown grayscale pictures of human faces without hair for 750 milliseconds, followed by a pause of 150 milliseconds. Then another face was shown for 150 milliseconds after which the volunteer reported whether it was the same face or not. The whole process was then repeated several times with different faces. The researchers then repeated the entire exercise but used simple, four-letter words. The researchers expected that those volunteers who had only their right hemisphere would do well at face recognition but not as well at word recognition, since the right hemisphere is generally used to process images while the left hemisphere processes words; they expected the opposite results for those who still had just their left hemisphere. Instead, the researchers found that both groups performed nearly equally well and both were on average 86% accurate on the tests compared to a control group consisting of people who had not undergone an hemispherectomy, with average 96% accuracy. The researchers also conducted a nearly identical experiment in which the faces and words were shown off to the left or right; both groups still did surprisingly well—but there was one interesting difference. In comparing their results with the control group, those who had undergone a hemispherectomy did as well as the control group in identifying images or words in two instances—when a word was placed on the left side, or a face on the right.

Michael C. Granovetter et al, With Childhood Hemispherectomy, One Hemisphere Can Support—But is Suboptimal for—Word and Face Recognition (2020). DOI: 10.1101/2020.11.06.371823

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